1. Field of the Invention
This invention is an article of manufacture and relates to reflectors, specifically, to a symmetrical reflector in the cross-sectional shape using two hyperbolas and fluorescent light fixtures utilizing such a reflector.
2. Description of Related Art
Other patents have taught how to use reflectors on light fixtures that have a cross-sectional shape generally hyperbolic, generally elliptic, or generally parabolic. For example, Reference 1 uses reflectors with elliptical cross-sections with the feature of one set of foci of the ellipses being coincident and with the other foci located at the ceiling level. These incandescent light fixtures use only reflected light with the embodiment designed such that all direct light coming from the light source is blocked. This patent would restrict the fixture to something small in diameter in order to meet the requirement of having one set of foci coincident. Having all direct light blocked seriously limits the efficiency of the lamp. A hyperbolic reflection surface is added to the lamp in another embodiment that is described, however, no diagram of the configuration is provided and the juxtaposition of the light source and the focus of the hyperbola is not taught.
Reference 2 claims a desk lamp with a reflector in the shape of a parabola formed from a series of triangular facets. This patent claims a method to approximately construct at reasonable cost, a curved reflection surface to improve the light delivery from the lamp.
Reference 3 claims a reflector, curvilinear in cross-sectional shape, and having tabs formed from part of the reflector surface for the purpose of socket protectors. The relative location of the light bulb to the reflector is not taught. Many other necessary features to define the embodiment of the reflector, such as the position of the light bulb relative to the focus of a conic section, is not taught. This embodiment utilizes a 300-watt light bulb, and therefore is not designed for energy savings but as a security lighting fixture.
Reference 4 is a lighting device having a plurality of linear surface mirrors, each partially surrounding a single light source. The reflector approximates an elliptical-shaped reflector. Its purpose is for use in a reproduction machine.
Reference 5 is a three-dimensional concavo-convex reflector for use as a headlamp on an automobile. At least part of the three-dimensional surface is formed having a hyperbolic curvature in the horizontal plane. It has a single light source. No attempt is made to provide energy savings.
Although there are a number of fluorescent light fixtures on the market, few seem to utilize the direct light and reflected light coming from the light source to full advantage. Reflection surfaces are painted milky white that has a medium reflectance. Some reflectors are being made on special order to retrofit existing light fixtures, reduce the number of fluorescent tubes, and thus improve the light efficiency and energy utilization. These retrofit reflectors are fabricated by bending them into rectangular facets thus approximating a parabola in cross-sectional shape. A highly reflective material, such as Silverlux by 3M Company applied to the surface of a thin aluminum sheet, is being used as the material for these reflectors. Since a parabolic reflector directs the light straight downward, the area of illumination between the rows of fixtures is lit only by direct light and receives very little of the reflected light. These installations tend to have a bright area under the fixture and a shadowy, dark area half way between fixtures. This non-uniform distribution of light is objectionable.
Generally, fluorescent light fixtures, which are designed to provide illumination for an area, should:
None of the above mentioned embodiments meet all five of these criteria. Accordingly, there is a need for new, optimized, efficient fluorescent light fixtures that will provide uniform light patterns coupled with an adequate level of illumination, and providing substantial energy savings. They must be suitable for use in new building construction or retrofit to existing structures, for illumination of art works or advertising signs, and for use in homes, stores, and offices.